Note 20 - Assets and Liabilities Measured and Reported at Fair Value - Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Securities available-for-sale, fair value	$ 574,524	$ 570,074
Fair Value, Measurements, Recurring [Member]
Securities available-for-sale, fair value	574,524	570,074
Interest rate swaps	579	178
Total assets	575,079	570,252
Interest rate swaps	259	203
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale, fair value	149,984	75,697
Interest rate swaps
Total assets	149,984	75,697
Interest rate swaps
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale, fair value	424,540	494,377
Interest rate swaps	579	178
Total assets	425,095	494,555
Interest rate swaps	259	203
US Treasury and Government [Member] \| Fair Value, Measurements, Recurring [Member]
Securities available-for-sale, fair value	149,984	74,998
US Treasury and Government [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale, fair value	149,984	74,998
US Treasury and Government [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale, fair value
US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale, fair value	213,844	268,090
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member]
Securities available-for-sale, fair value	213,844	268,090
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale, fair value
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale, fair value	213,844	268,090
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available-for-sale, fair value	161,507	168,843
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] \| Fair Value, Measurements, Recurring [Member]
Securities available-for-sale, fair value	161,507	168,843
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale, fair value
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale, fair value	161,507	168,843
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale, fair value	49,189	57,444
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member]
Securities available-for-sale, fair value	49,189	57,444
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale, fair value
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale, fair value	$ 49,189	57,444
Common Stock [Member]
Securities available-for-sale, fair value		699
Common Stock [Member] \| Fair Value, Measurements, Recurring [Member]
Securities available-for-sale, fair value		699
Common Stock [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale, fair value		699
Common Stock [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale, fair value

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562

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Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611

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- Definition

Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

+ References

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